text: p-Toluenesulfonic acid (PTSA, pTSA, or pTsOH) or tosylic acid (TsOH) is an organic compound with the formula CHCHSOH. It is a white extremely hygroscopic solid that is soluble in water, alcohols, and other polar organic solvents. The CHCHSO group is known as the tosyl group and is often abbreviated as Ts or Tos. Most often, TsOH refers to the monohydrate, TsOHHO.
  As with other aryl sulfonic acids, TsOH is a strong organic acid.  It is about one million times stronger than benzoic acid.  It is one of the few strong acids that is solid and therefore is conveniently weighed and stored.